Another Republican-backed group, Maine Freedom, approached the race from a different angle. It started airing ads in late August urging Democrats to back Dill over King, apparently in an effort to peel support away from the independent who supports President Barack Obama’s re-election and supports the Obama administration’s health care reform law. Maine Freedom spent $359,000 total in August and September.

The National Republican Senatorial Committee also joined the anti-King ad wars in September, with accusations related to King’s wind energy business before King boosters shot back.

The effect of the nearly $7.4 million outside groups have poured into Maine’s Senate race is debatable. Polls released over the weekend show the race dynamics didn’t change much from where they were June, but one thing that’s certain is the outside spending became a constant topic of discussion among the candidates.

Dill, who’s struggled to build momentum for her campaign and attract substantial support from her own party, has continued to claim she’s the one truly independent candidate unbeholden to the whims of outside spenders.

Independents Andrew Ian Dodge — who originally joined the Republican primary to challenge Snowe when she was still considering a run for re-election — and Danny Dalton also joined the campaign for the Senate seat.